The main objective of this project is to identify improved therapeufic opfions for pafients with CML. Imafinib is standard therapy for CML, but neariy 20% of patients never achieve complete cytogenetic remission, and most have residual disease by polymerase chain reacfion, and 10-15% of those who achieve remission eventually progress. More potent tyrosine kinase inhibitors (TKI) such as dasatinib and nilotinib have significant clinical activity after imatinib failure. The first aim is to determine whether dasatinib or nilotinib may improve the molecular response, and event-free and progression-free survival of patients with newly diagnosed chronic phase CML. Pafients will be treated in one of two parallel studies with the primary objective to improve the molecular response rate at 12 months. The second aim is to invesfigate whether immunotherapy, in the form of PRI vaccine, can improve molecular responses of patients with minimal residual disease on imatinib therapy. Because Interferon may improve the expression of proteinase 3 from which PRI is derived, patients with this phenotype will be randomized to receive PRI and imatinib, with or without interferon. The primary objective is to improve the molecular response with PRI vaccine. Based on data originated through this grant suggesting activation of JAK2 in Bcr-Abl-posifive cells, the third aim is to invesfigate whether JAK2 inhibition may have clinical activity in CML pafients refractory to TKI. We will conduct a phase 2 trial of INCB18424, a JAK2 inhibitor, in patients who failed at least 2 TKI. The long-term plan is to use this agent in combination with TKI. The fourth aim deals with the problem of patients with blast phase, a group with dismal outcome with available therapy. Dasatinib induces high response rates but most patients eventually relapse. Increased methylafion is associated with progression in CML. We will thus treat patients with blast phase CML with decitabine, a hypomethylating agent, and dasafinib to determine whether this combinafion may improve the rate and durability of responses in blast phase CML. Overall, this project may lead to improved long-term outcome for patients with all phases ofthe disease and get us closer to complete eradication of CML.